A conventional wheel stop apparatus, an example of which is shown in FIG. 1, is comprised of a ramp board 15 pivotally mounted to one end edge of a bottom plate 9 by a support shaft 5. The other end edge of the ramp board 15 is pivotably mounted upon the ends of a substantially U-shaped member 7 formed by the bending of a rod-like material. Such a structure is expensive in cost and heavy in weight because of the different types of plates, rods, shafts and the various types of materials needed to form such plates, rods, shafts, and the like. Furthermore, many man-hours are demanded for fabrication thereof.
In order to remedy such drawbacks, the present applicant invented a wheel stop apparatus according to the structure shown in FIG. 2, for which U.S. Pat. No. 4,109,763 was granted. The apparatus of U.S. Pat. No. 4,109,763 provides a structure that is fitted between a groove 33 of a support plate 23 having a broad bearing portion 25 secured to a stopper plate 15. The apparatus disclosed in U.S. Pat. No. 4,109,763 has a problem with instability due to an oscillating effect which occurred between the stopper plate 15 and the support plate 23.